1. Field of the Invention
The present invention generally relates to a reader/writer for reading and writing information on IC tags and IC cards in a non-contact manner and a manufacturing method thereof.
2. Description of the Related Art
Nowadays, IC tags (also referred to as RFID tags) and IC cards are attached to objects of products and substances (hereafter referred to as objects) for information management. Information about the objects obtained from the IC tags via a reader/writer is managed using a computer in order to improve the efficiency of business.
FIG. 1 is a plan view showing a conventional reader/writer. As shown in FIG. 1, a reader/writer 100 comprises a circuit board 101, a communication control portion 102, a matching circuit portion 103, an antenna 104, and a mold resin 105.
The circuit board 101 includes a conductor pattern such as wiring, vias (neither is shown in the drawings), and the like. The communication control portion 102, the matching circuit portion 103, and the antenna 104 are mounted on the same plane of the circuit board 101. The communication control portion 102 comprises an IC chip, a passive component such as LCR, and the like and the communication control portion 102 is sealed with the mold resin 105. The communication control portion 102 is configured to transmit/receive information with IC tags via the antenna 104 and electrically connected to the matching circuit portion 103.
The matching circuit portion 103 is electrically connected to the antenna 104 and the communication control portion 102. The matching circuit portion 103 is configured to perform matching in accordance with the frequency of electromagnetic waves used for communication and the impedance of input/output.
The antenna 104 is disposed on the circuit board 101 such that the antenna 104 surrounds the communication control portion 102. The antenna 104 is configured to supply IC tags with electric power and transmit/receive information via electromagnetic induction (refer to Patent document 1, for example).
Patent Document 1: Japanese Laid-Open Patent Application No. 2005-12673
However, in the conventional reader/writer 100, the communication control portion 102, the matching circuit portion 103, and the antenna 104 are mounted on the same plane of the circuit board 101, so that the size of the circuit board 101 is increased. This is problematic in that miniaturizing the reader/writer 100 is difficult.
FIG. 2 is a schematic diagram showing the relationship between a magnetic flux generated from an antenna and an eddy current. In FIG. 2, the same components as in the reader/writer 100 shown in FIG. 1 are provided with the same numerical reference.
Further, when the circuit board 101 including the antenna 104 is assumed to be embedded in other device, the circuit board 101 may be disposed on a metallic material 106 (such as other circuit board, a battery, a frame, or the like) due to the restriction of position. In this case, a magnetic flux B1 generated from the antenna 104 collides with the metallic material 106 and an eddy current I1 is generated on a surface of the metallic material 106. Because of the eddy current I1, a new magnetic flux B2 is generated and the magnetic flux B1 is attenuated. This is problematic in that the reliability of communication between IC tags and the reader/writer 100 is reduced.